Bremner, MJ, Jozsa, R & Shepherd, D 2011, 'Classical simulation of commuting quantum computations implies collapse of the polynomial hierarchy', Proceedings Of The Royal Society A-Mathematical Physical And Engineering Sciences, vol. 467, no. 2126, pp. 459-472.
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We consider quantum computations comprising only commuting gates, known as IQP computations, and provide compelling evidence that the task of sampling their output probability distributions is unlikely to be achievable by any efficient classical means. More specifically, we introduce the class post-IQP of languages decided with bounded error by uniform families of IQP circuits with post-selection, and prove first that post-IQP equals the classical class PP. Using this result we show that if the output distributions of uniform IQP circuit families could be classically efficiently sampled, either exactly in total variation distance or even approximately up to 41 per cent multiplicative error in the probabilities, then the infinite tower of classical complexity classes known as the polynomial hierarchy would collapse to its third level. We mention some further results on the classical simulation properties of IQP circuit families, in particular showing that if the output distribution results from measurements on only O(log n) lines then it may, in fact, be classically efficiently sampled.
Cha, DF, Zhang, H & Blumenstein, M 2011, 'Prediction of maximum wave-induced liquefaction in porous seabed using multi-artificial neural network model', OCEAN ENGINEERING, vol. 38, no. 7, pp. 878-887.
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Chen, J, Chen, X, Duan, R, Ji, Z & Zeng, B 2011, 'No-go Theorem For One-way Quantum Computing On Naturally Occurring Two-level Systems', Physical Review A, vol. 83, no. 5, pp. 0-0.
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The ground states of some many-body quantum systems can serve as resource states for the one-way quantum computing model, achieving the full power of quantum computation. Such resource states are found, for example, in spin- 5 2 and spin- 3 2 systems. It is, of course, desirable to have a natural resource state in a spin- 1 2 , that is, qubit system. Here, we give a negative answer to this question for frustration-free systems with two-body interactions. In fact, it is shown to be impossible for any genuinely entangled qubit state to be a nondegenerate ground state of any two-body frustration-free Hamiltonian. What is more, we also prove that every spin- 1 2 frustration-free Hamiltonian with two-body interaction always has a ground state that is a product of single- or two-qubit states. In other words, there cannot be any interesting entanglement features in the ground state of such a qubit Hamiltonian.
Datta, N & Hsieh, M-H 2011, 'The apex of the family tree of protocols: optimal rates and resource inequalities', NEW JOURNAL OF PHYSICS, vol. 13.
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Devitt, SJ, Munro, WJ & Nemoto, K 2011, 'High performance quantum computing', Progress in Informatics, no. 8, pp. 49-55.
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The architecture scalability afforded by recent proposals of a large-scale photonic-based quantum computer allows us to move on to a discussion of massively scaled Quantum Information Processing (QIP). In this paper, we consider the quantum analogue of High Performance Computing (HPC), where a dedicated server farm is utilized by many users to run algorithms and share quantum data. We introduce both a trusted mainframe model as a quantum extension of classical HPC and a model where quantum security is achieved during computation. The scaling structure of the optical architecture leads to an attractive future for server based QIP, where dedicated mainframes can be constructed and/or expanded to serve an increasingly hungry user base with the ideal resource for individual quantum information processing. © 2011 National Institute of Informatics.
Devitt, SJ, Stephens, AM, Munro, WJ & Nemoto, K 2011, 'Integration of highly probabilistic sources into optical quantum architectures: perpetual quantum computation', NEW JOURNAL OF PHYSICS, vol. 13.
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Ferrie, C 2011, 'Quasi-probability representations of quantum theory with applications to quantum information science', REPORTS ON PROGRESS IN PHYSICS, vol. 74, no. 11.
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Gerrits, T, Thomas-Peter, N, Gates, JC, Lita, AE, Metcalf, BJ, Calkins, B, Tomlin, NA, Fox, AE, Linares, AL, Spring, JB, Langford, NK, Mirin, RP, Smith, PGR, Walmsley, IA & Nam, SW 2011, 'On-chip, photon-number-resolving, telecommunication-band detectors for scalable photonic information processing', PHYSICAL REVIEW A, vol. 84, no. 6.
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Hsieh, M & Le Gall, F 2011, 'NP-hardness of decoding quantum error-correction codes', Physical Review A, vol. 83, no. 5, pp. 1-5.
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Though the theory of quantum error correction is intimately related to the classical coding theory, in particular, one can construct quantum error correction codes (QECCs) from classical codes with the dual containing property, this does not necessarily imply that the computational complexity of decoding QECCs is the same as their classical counterparts. Instead, decoding QECCs can be very much different from decoding classical codes due to the degeneracy property. Intuitively, one expect degeneracy would simplify the decoding since two different errors might not and need not be distinguished in order to correct them. However, we show that general quantum decoding problem is NP-hard regardless of the quantum codes being degenerate or non-degenerate. This finding implies that no considerably fast decoding algorithm exists for the general quantum decoding problems, and suggests the existence of a quantum cryptosystem based on the hardness of decoding QECCs.
Hsieh, M, Yen, W & Hsu, L 2011, 'High Performance Entanglement-Assisted Quantum LDPC Codes Need Little Entanglement', IEEE Transactions On Information Theory, vol. 57, no. 3, pp. 1761-1769.
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Though the entanglement-assisted formalism provides a universal connection between a classical linear code and an entanglement-assisted quantum error-correcting code (EAQECC), the issue of maintaining large amount of pure maximally entangled states in constructing EAQECCs is a practical obstacle to its use. It is also conjectured that the power of entanglement-assisted formalism to convert those good classical codes comes from massive consumption of maximally entangled states. We show that the above conjecture is wrong by providing families of EAQECCs with an entanglement consumption rate that diminishes linearly as a function of the code length. Notably, two families of EAQECCs constructed in the paper require only one copy of maximally entangled state no matter how large the code length is. These families of EAQECCs that are constructed from classical finite geometric LDPC codes perform very well according to our numerical simulations. Our work indicates that EAQECCs are not only theoretically interesting, but also physically implementable. Finally, these high performance entanglement-assisted LDPC codes with low entanglement consumption rates allow one to construct high-performance standard QECCs with very similar parameters.
Jain, R, Ji, Z, Upadhyay, S & Watrous, J 2011, 'QIP = PSPACE', JOURNAL OF THE ACM, vol. 58, no. 6.
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Ji, Z, Wei, Z & Zeng, B 2011, 'Complete characterization of the ground-space structure of two-body frustration-free Hamiltonians for qubits', PHYSICAL REVIEW A, vol. 84, no. 4.
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Langford, NK, Ramelow, S, Prevedel, R, Munro, WJ, Milburn, GJ & Zeilinger, A 2011, 'Efficient quantum computing using coherent photon conversion', NATURE, vol. 478, no. 7369, pp. 360-363.
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Lapkiewicz, R, Li, P, Schaeff, C, Langford, NK, Ramelow, S, Wiesniak, M & Zeilinger, A 2011, 'Experimental non-classicality of an indivisible quantum system', NATURE, vol. 474, no. 7352, pp. 490-493.
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Lee, J, Guan, H, Loo, Y-C, Blumenstein, M & Wang, X-P 2011, 'Modelling Long-term Bridge Deterioration at Structural Member Level Using Artificial Intelligence Techniques', ARCHITECTURE AND BUILDING MATERIALS, PTS 1 AND 2, vol. 99-100, pp. 444-+.
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Lee, KC, Sprague, MR, Sussman, BJ, Nunn, J, Langford, NK, Jin, X-M, Champion, T, Michelberger, P, Reim, KF, England, D, Jaksch, D & Walmsley, IA 2011, 'Entangling Macroscopic Diamonds at Room Temperature', SCIENCE, vol. 334, no. 6060, pp. 1253-1256.
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Lee, T, Mittal, R, Reichardt, BW, palek, R & Szegedy, M 2011, 'Quantum Query Complexity of State Conversion', 2011 IEEE 52nd Annual Symposium on Foundations of Computer Science.
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Liu, W & Li, S 2011, 'On standard models of fuzzy Region Connection Calculus', International Journal of Approximate Reasoning, vol. 52, no. 9, pp. 1337-1354.
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The Region Connection Calculus (RCC) is perhaps the most influential topological relation calculus. Based on the first-order logic, the RCC, however, does not fully meet the needs of applications where the vagueness of entities or relations is important and not ignorable. This paper introduces standard models for the fuzzy region connection calculus (RCC) proposed by Schockaert et al. (2008) [18]. Each of such a standard fuzzy RCC model is induced by a standard RCC model in a natural way. We prove that each standard fuzzy RCC model is canonical in the sense that any satisfiable set of fuzzy RCC8 constraints have a solution in it. Apolynomial realization algorithm is also provided. As a side product,we showsimilar sets of fuzzy constraints have similar solutions if both are satisfiable. This allows us to approximate fuzzy RCC constraints that have arbitrary bounds by those have bounds with finite precision. © 2011 Published by Elsevier Inc.
Liu, W & Li, S 2011, 'Reasoning about Cardinal Directions between Extended Objects: The NP-Hardness Result', Artificial Intelligence Journal, vol. 175, no. 18, pp. 2155-2169.
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Weiming Liu, Sanjiang Li.Reasoning about Cardinal Directions between Extended Objects: The NP-Hardness Result. Artificial Intelligence, 2011, 175(18): 2155-2169.
Ocko, SA, Chen, X, Zeng, B, Yoshida, B, Ji, Z, Ruskai, MB & Chuang, IL 2011, 'Quantum Codes Give Counterexamples to the Unique Preimage Conjecture of the N-Representability Problem', PHYSICAL REVIEW LETTERS, vol. 106, no. 11.
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Reim, KF, Michelberger, P, Lee, KC, Nunn, J, Langford, NK & Walmsley, IA 2011, 'Single-Photon-Level Quantum Memory at Room Temperature', PHYSICAL REVIEW LETTERS, vol. 107, no. 5.
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Rohde, PP & Ralph, TC 2011, 'Time-resolved detection and mode mismatch in a linear optics quantum gate', NEW JOURNAL OF PHYSICS, vol. 13.
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Rohde, PP, Schreiber, A, Stefanak, M, Jex, I & Silberhorn, C 2011, 'Multi-walker discrete time quantum walks on arbitrary graphs, their properties and their photonic implementation', NEW JOURNAL OF PHYSICS, vol. 13.
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Thomas-Peter, N, Langford, NK, Datta, A, Zhang, L, Smith, BJ, Spring, JB, Metcalf, BJ, Coldenstrodt-Ronge, HB, Hu, M, Nunn, J & Walmsley, IA 2011, 'Integrated photonic sensing', New Journal of Physics, vol. 13.
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Loss is a critical roadblock to achieving photonic quantum-enhanced technologies. We explore a modular platform for implementing integrated photonics experiments and consider the effects of loss at different stages of these experiments, including state preparation, manipulation and measurement. We frame our discussion mainly in the context of quantum sensing and focus particularly on the use of loss-tolerant Holland-Burnett states for optical phase estimation. In particular, we discuss spontaneous four-wave mixing in standard birefringent fibre as a source of pure, heralded single photons and present methods of optimizing such sources. We also outline a route to programmable circuits that allows the control of photonic interactions even in the presence of fabrication imperfections and describe a ratiometric characterization method for beam splitters, which allows the characterization of complex circuits without the need for full process tomography. Finally, we present a framework for performing state tomography on heralded states using lossy measurement devices. This is motivated by a calculation of the effects of fabrication imperfections on precision measurement using Holland-Burnett states. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Tomamichel, M & Renner, R 2011, 'Uncertainty Relation for Smooth Entropies', PHYSICAL REVIEW LETTERS, vol. 106, no. 11.
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Tomamichel, M, Schaffner, C, Smith, A & Renner, R 2011, 'Leftover Hashing Against Quantum Side Information', IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 57, no. 8, pp. 5524-5535.
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Winkler, S, Tomamichel, M, Hengl, S & Renner, R 2011, 'Impossibility of Growing Quantum Bit Commitments', PHYSICAL REVIEW LETTERS, vol. 107, no. 9.
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Ying, M 2011, 'Floyd-hoare Logic For Quantum Programs', ACM Transactions pn Programming Language and Systems (TOPLAS), vol. 33, no. 6, pp. 1-49.
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Floyd-Hoare logic is a foundation of axiomatic semantics of classical programs, and it provides effective proof techniques for reasoning about correctness of classical programs. To offer similar techniques for quantum program verification and to build a
Ying, M & Feng, Y 2011, 'A Flowchart Language For Quantum Programming', IEEE Transactions On Software Engineering, vol. 37, no. 4, pp. 466-485.
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Several high-level quantum programming languages have been proposed in the previous research. In this paper, we define a low-level flowchart language for quantum programming, which can be used in implementation of high-level quantum languages and in desi
Yu, N, Duan, R & Ying, M 2011, 'Any 2 Circle Times N Subspace Is Locally Distinguishable', Physical Review A, vol. 84, no. 1, pp. 1-3.
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A subspace of a multipartite Hilbert space is said to be locally indistinguishable if any orthonormal basis of this subspace cannot be perfectly distinguished by local operations and classical communication. Previously it was shown that any m . n bipartite system with m > 2 and n > 2 has a locally indistinguishable subspace. However, it has been an open problem since 2005 whether there is a locally indistinguishable bipartite subspace with a qubit subsystem.We settle this problem in negative by showing that any 2 . n bipartite subspace contains a basis that is locally distinguishable. As an interesting application, we show that any quantum channel with two Kraus operators has optimal environment-assisted classical capacity.
Babai, L, Codenotti, P, Grochow, JA & Qiao, Y 2011, 'Code equivalence and group isomorphism', Proceedings of the twenty-second annual ACM-SIAM symposium on Discrete Algorithm, ACM/SIAM Symposium on Discrete Algorithms, ACM, San Francisco, USA, pp. 1395-1408.
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The isomorphism problem for groups given by their multiplication tables has long been known to be solvable in time nlog n+O(1). The decades-old quest for a polynomial-time algorithm has focused on the very difficult case of class-2 nilpotent groups (groups whose quotient by their center is abelian), with little success. In this paper we consider the opposite end of the spectrum and initiate a more hopeful program to find a polynomial-time algorithm for semisimple groups, defined as groups without abelian normal subgroups. First we prove that the isomorphism problem for this class can be solved in time nO(log log n). We then identify certain bottlenecks to polynomial-time solvability and give a polynomial-time solution to a rich subclass, namely the semisimple groups where each minimal normal subgroup has a bounded number of simple factors. We relate the results to the filtration of groups introduced by Babai and Beals (1999). One of our tools is an algorithm for equivalence of (not necessarily linear) codes in simply-exponential time in the length of the code, obtained by modifying Luks's algorithm for hypergraph isomorphism in simply-exponential time in the number of vertices (FOCS 1999). We comment on the complexity of the closely related problem of permutational isomorphism of permutation groups.
Bremner, MJ 2011, 'Classical simulation of commuting quantum computations implies collapse of the polynomial hierarchy', 14th Workshop on Quantum Information Processing, Singapore.
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Quantum Information Processing (QIP) is a rapidly developing field of research spanning both physics and computer science. As the name implies, the field extends information processing (including computing and cryptography) to physical regimes where quantum effects become significant. QIP 2011 was the fourteenth workshop on theoretical aspects of quantum computing, quantum cryptography, and quantum information in a series that started in Aarhus in 1998 and was held 2010 at ETH Zurich, Switzerland. QIP 2011 featured a tutorial programme, invited talks, contributed talks, and a poster session. In addition, there was a rump session with short informal talks.
Devitt, SJ, Stephens, AM, Munro, WJ & Nemoto, K 2011, 'Integration of highly probabilistic sources into optical quantum architectures', Optics InfoBase Conference Papers, pp. 423-425.
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We introduce a design for an optical computer constructed exclusively from a single quantum component. Unlike previous efforts we eliminate the need for on demand photon sources and detectors and replace them with the same device utilised to create photon/photon entanglement. This introduces highly probabilistic elements into the architecture while maintaining complete specificity of the structure and operation for a large-scale computer. © 2011 AOS.
Devitt, SJ, Stephens, AM, Munro, WJ & Nemoto, K 2011, 'The Optical Quantum Computer: How big and how fast?', QUANTUM COMMUNICATIONS AND QUANTUM IMAGING IX, Conference on Quantum Communications and Quantum Imaging IX, SPIE-INT SOC OPTICAL ENGINEERING, San Diego, CA.
Devitt, SJ, Stephens, AM, Munro, WJ & Nemoto, K 2011, 'The Optical Quantum Computer: How big and how fast?', QUANTUM COMMUNICATIONS AND QUANTUM IMAGING IX, Conference on Quantum Communications and Quantum Imaging IX, SPIE-INT SOC OPTICAL ENGINEERING, San Diego, CA.
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Duan, R, Severini, S & Winter, A 2011, 'Zero-error communication via quantum channels and a quantum Lovász Θ-function', 2011 IEEE International Symposium on Information Theory Proceedings (ISIT), IEEE International Symposium on Information Theory, IEEE, St Petersburg, Russia, pp. 64-68.
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We study the quantum channel version of Shannon's zero-error capacity problem. Motivated by recent progress on this question, we propose to consider a certain linear space operators as the quantum generalisation of the adjacency matrix, in terms of which the plain, quantum and entanglement-assisted capacity can be formulated, and for which we show some new basic properties. Most importantly, we define a quantum version of Lova´sz' famous ? function, as the norm-completion (or stabilisation) of a naive generalisation of ?. We go on to show that this function upper bounds the number of entanglement-assisted zero-error messages, that it is given by a semidefinite programme, whose dual we write down explicitly, and that it is multiplicative with respect to the natural (strong) graph product. We explore various other properties of the new quantity, which reduces to Lova´sz' original ? in the classical case, give several applications, and propose to study the linear spaces of operators associated to channels as non-commutative graphs, using the language of operator systems and Hilbert modules.
Feng, Y, Duan, R & Ying, M 2011, 'Bisimulation for Quantum Processes', Proceedings of the 38th annual ACM SIGPLAN-SIGACT symposium on Principles of programming language, ACM-SIGACT Symposium on Principles of Programming Languages, ACM, Austin, Texas, USA, pp. 523-534.
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Quantum cryptographic systems have been commercially available, with a striking advantage over classical systems that their security and ability to detect the presence of eavesdropping are provable based on the principles of quantum mechanics. On the other hand, quantum protocol designers may commit much more faults than classical protocol designers since human intuition is much better adapted to the classical world than the quantum world. To offer formal techniques for modeling and verification of quantum protocols, several quantum extensions of process algebra have been proposed. One of the most serious issues in quantum process algebra is to discover a quantum generalization of the notion of bisimulation, which lies in a central position in process algebra, preserved by parallel composition in the presence of quantum entanglement, which has no counterpart in classical computation. Quite a few versions of bisimulation have been defined for quantum processes in the literature, but in the best case they are only proved to be preserved by parallel composition of purely quantum processes where no classical communications are involved. Many quantum cryptographic protocols, however, employ the LOCC (Local Operations and Classical Communications) scheme, where classical communications must be explicitly specified. So, a notion of bisimulation preserved by parallel composition in the circumstance of both classical and quantum communications is crucial for process algebra approach to verification of quantum cryptographic protocols. In this paper we introduce a novel notion of bisimulation for quantum processes and prove that it is congruent with respect to various process algebra combinators including parallel composition even when both classical and quantum communications are present.We also establish some basic algebraic laws for this bisimulation.
Fujiwara, Y & Hsieh, M 2011, 'Adaptively correcting quantum errors with entanglement', 2011 IEEE International Symposium on Information Theory Proceedings (ISIT), IEEE International Symposium on Information Theory, IEEE, St Petersburg, pp. 279-283.
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Contrary to the assumption that most quantum error-correcting codes (QECC) make, it is expected that phase errors are much more likely than bit errors in physical devices. By employing the entanglement-assisted stabilizer formalism, we develop a new kind of error-correcting protocol which can flexibly trade error correction abilities between the two types of errors, such that high error correction performance is achieved both in symmetric and in asymmetric situations. The characteristics of the QECCs can be optimized in an adaptive manner during information transmission. The proposed entanglement-assisted QECCs require only one ebit regardless of the degree of asymmetry at a given moment and can be decoded in polynomial time.
Jansen, M, Qiao, Y & Sarma, MNJ 2010, 'Deterministic Black-Box Identity Testing pi-Ordered Algebraic Branching Programs', IARCS International Conference on Foundations of Software Technology and Theoretical Computer Science, International Conference on Foundations of Software Technology and Theoretical Computer Science, Dagstuhl Publishing, Chennai, India, pp. 296-307.
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In this paper we study algebraic branching programs (ABPs) with restrictions on the order and the number of reads of variables in the program. An ABP is given by a layered directed acyclic graph with source $s$ and sink $t$, whose edges are labeled by variables taken from the set $\{x_1, x_2, \ldots, x_n\}$ or field constants. It computes the sum of weights of all paths from $s$ to $t$, where the weight of a path is defined as the product of edge-labels on the path. Given a permutation $\pi$ of the $n$ variables, for a $\pi$-ordered ABP ($\pi$-OABP), for any directed path $p$ from $s$ to $t$, a variable can appear at most once on $p$, and the order in which variables appear on $p$ must respect $\pi$. One can think of OABPs as being the arithmetic analogue of ordered binary decision diagrams (OBDDs). We say an ABP $A$ is of read $r$, if any variable appears at most $r$ times in $A$. Our main result pertains to the polynomial identity testing problem, i.e. the problem of deciding whether a given $n$-variate polynomial is identical to the zero polynomial or not. We prove that over any field $\F$, and in the black-box model, i.e. given only query access to the polynomial, read $r$ $\pi$-OABP computable polynomials can be tested in $\DTIME[2^{O(r\log r \cdot \log^2 n \log\log n)}]$. In case $\F$ is a finite field, the above time bound holds provided the identity testing algorithm is allowed to make queries to extension fields of $\F$.
Lane, C, Gal, Y, Browne, M, Short, A, Strauss, D, Tomlinson, R, Jackson, K, Tan, C & Blumenstein, M 2011, 'A new technique for measuring breaking wave dynamics, heights and periods', 20th Australasian Coastal and Ocean Engineering Conference 2011 and the 13th Australasian Port and Harbour Conference 2011, COASTS and PORTS 2011, pp. 277-280.
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A new system for measuring breakzone dynamics, breaking wave heights and wave periods across the surfzone from a digital video sequence is presented. The WavePack system was tested using a set of 39 video files covering a range of wave heights and conditions on different days. The relatively low percentage of rejected wave counts supports the flexibility of the wave height processing algorithm to perform in the highly variable wave conditions. The processed wave heights correlated highly with the independent sources of wave height available having a correlation of 0.86 to manual counts and 0.85 with NOAA WW3 significant wave height. It was found that the WavePack system can provide a low cost, robust, reliable and accurate system for measuring continuous wave height from a low elevation video camera aimed at the target beach under a wide range of wave conditions.
Liu, W, Wang, S, Li, S & Liu, D 2011, 'Solving Qualitative Constraints Involving Landmarks', The 17th International Conference on Principles and Practice of Constraint Programming, International Conference on Principles and Practice, Springer-Verlag Berlin / Heidelberg, Perugia, Italy, pp. 523-537.
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Consistency checking plays a central role in qualitative spatial and temporal reasoning. Given a set of variables V , and a set of constraints Î taken from a qualitative calculus (e.g. the Interval Algebra (IA) or RCC-8), the aim is to decide if Î is consistent. The consistency problem has been investigated extensively in the literature. Practical applications e.g. urban planning often impose, in addition to those between undetermined entities (variables), constraints between determined entities (constants or landmarks) and variables. This paper introduces this as a new class of qualitative constraint satisfaction problems, and investigates the new consistency problem in several well-known qualitative calculi, e.g. IA, RCC-5, and RCC-8.We show that the usual local consistency checking algorithm works for IA but fails in RCC-5 and RCC-8. We further show that, if the landmarks are represented by polygons, then the new consistency problem of RCC-5 is tractable but that of RCC-8 is NP-complete.
Liwicki, M, Malik, MI, Heuvel, CEVD, Chen, X, Berger, C, Stoel, R, Blumenstein, M & Found, B 2011, 'Signature verification competition for online and offline skilled forgeries (SigComp2011)', Proceedings of the International Conference on Document Analysis and Recognition, ICDAR, International Conference on Document Analysis and Recognition (ICDAR), IEEE, Beijing, China, pp. 1480-1484.
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The Netherlands Forensic Institute and the Institute for Forensic Science in Shanghai are in search of a signature verification system that can be implemented in forensic casework and research to objectify results. We want to bridge the gap between recent technological developments and forensic casework. In collaboration with the German Research Center for Artificial Intelligence we have organized a signature verification competition on datasets with two scripts (Dutch and Chinese) in which we asked to compare questioned signatures against a set of reference signatures. We have received 12 systems from 5 institutes and performed experiments on online and offline Dutch and Chinese signatures. For evaluation, we applied methods used by Forensic Handwriting Examiners (FHEs) to assess the value of the evidence, i.e., we took the likelihood ratios more into account than in previous competitions. The data set was quite challenging and the results are very interesting. © 2011 IEEE.
Munro, WJ, Devitt, SJ & Nemoto, K 2011, 'Designing quantum repeaters and networks', QUANTUM COMMUNICATIONS AND QUANTUM IMAGING IX, Conference on Quantum Communications and Quantum Imaging IX, SPIE-INT SOC OPTICAL ENGINEERING, San Diego, CA.
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Munro, WJ, Devitt, SJ, Stephens, AM & Nemoto, K 2010, 'High Bandwidth Quantum Communication', QUANTUM COMMUNICATION, MEASUREMENT AND COMPUTING (QCMC): THE TENTH INTERNATIONAL CONFERENCE, 10th International Conference on Quantum Communication, Measurement and Computing (QCMC), AMER INST PHYSICS, Brisbane, AUSTRALIA.
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Munro, WJ, Stephens, AM, Devitt, SJ & Nemoto, K 2011, 'Quantum communication without memories or shared entanglement', Optics InfoBase Conference Papers, pp. 413-414.
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Long-range quantum communication and its associated repeater network are a necessity for any future quantum Internet. The performance of such networks is currently limited by the time it takes to establish entangled links between the appropriate parties on the network. Typically this scales as the round trip time for a signal to be transmitted between those parties. We present in this talk the design of a communications network for the direct transfer of quantum information where the rate at which quantum data can be transmitted is not limited by the distance the information needs to be sent but instead by the time to perform efficient local gate operations. Our scheme requires neither the establishment of entanglement between communication nodes nor the use of long-lived quantum memories. Our scheme thus provides a much higher communications rate than in standard teleportation based schemes. © 2011 AOS.
Munro, WJ, Stephens, AM, Devitt, SJ & Nemoto, K 2011, 'Quantum communication without memories or shared entanglement', 2011 Int. Quantum Electron. Conf., IQEC 2011 and Conf. Lasers and Electro-Optics, CLEO Pacific Rim 2011 Incorporating the Australasian Conf. Optics, Lasers and Spectroscopy and the Australian Conf., pp. 413-414.
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Long-range quantum communication and its associated repeater network are a necessity for any future quantum Internet. The performance of such networks is currently limited by the time it takes to establish entangled links between the appropriate parties on the network. Typically this scales as the round trip time for a signal to be transmitted between those parties. We present in this talk the design of a communications network for the direct transfer of quantum information where the rate at which quantum data can be transmitted is not limited by the distance the information needs to be sent but instead by the time to perform efficient local gate operations. Our scheme requires neither the establishment of entanglement between communication nodes nor the use of long-lived quantum memories. Our scheme thus provides a much higher communications rate than in standard teleportation based schemes. © 2011 IEEE.
Nemoto, K, Devitt, SJ, Stephens, AM & Munro, WJ 2011, 'Integration of highly probabilistic sources into optical quantum architectures', Optics InfoBase Conference Papers.
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We introduce a design for an optical computer constructed exclusively from a single quantum component. Unlike previous efforts we eliminate the need for on demand photon sources and detectors and replace them with the same device utilised to create photon/photon entanglement. This introduces highly probabilistic elements into the architecture while maintaining complete specificity of the structure and operation for a large scale computer. © 2011 Optical Society of America.
Nguyen, V & Blumenstein, M 2011, 'An application of the 2D Gaussian filter for enhancing feature extraction in off-line signature verification', Proceedings of the International Conference on Document Analysis and Recognition, ICDAR, International Conference on Document Analysis and Recognition (ICDAR), IEEE, Beijing, China, pp. 339-343.
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Similar to many other pattern recognition problems, feature extraction contributes significantly to the overall performance of an off-line signature verification system. To be successful, a feature extraction technique must be tolerant to different types of variation whilst preserving essential information of input patterns. In this paper, we describe a grid-based feature extraction technique that utilises directional information extracted from the signature contour, i.e. the chain code histogram. Our experimental results for signature verification indicated that, by applying a suitable 2D Gaussian filter on the matrices containing the chain code histograms, an average error rate (AER) of 13.90% can be obtained whilst maintaining the false acceptance rate (FAR) for random forgeries as low as 0.02%. These figures are comparable or better than those reported by other state of the art feature extraction techniques such as the Modified Direction Feature (MDF) and the Gradient feature. © 2011 IEEE.
Pal, S, Blumenstein, M & Pal, U 2011, 'Non-english and non-latin signature verification systems: A survey', CEUR Workshop Proceedings, International Workshop on Automated Forensic Handwriting Analysis, CEUR, Beijing, China, pp. 1-5.
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Signatures continue to be an important biometric because they remain widely used as a means of personal verification and therefore an automatic verification system is needed. Manual signature-based authentication of a large number of documents is a difficult and time consuming task. Consequently for many years, in the field of protected communication and financial applications, we have observed an explosive growth in biometric personal authentication systems that are closely connected with measurable unique physical characteristics (e.g. hand geometry, iris scan, finger prints or DNA) or behavioural features. Substantial research has been undertaken in the field of signature verification involving English signatures, but to the best of our knowledge, very few works have considered non-English signatures such as Chinese, Japanese, Arabic etc. In order to convey the state-of-the-art in the field to researchers, in this paper we present a survey of non-English and non-Latin signature verification systems.
Pal, S, Blumenstein, M & Pal, U 2011, 'Off-line signature verification systems: A survey', International Conference and Workshop on Emerging Trends in Technology 2011, ICWET 2011 - Conference Proceedings, International Conference & Workshop on Emerging Trends in Technology, ACM, Mumbai, Maharashtra, India, pp. 652-657.
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Signatures are extensively used as a means of personal verification. Manual signature-based authentication of a large number of documents is a very difficult and time consuming task. Consequently for many years, in the field of protected communication and financial applications, we have observed an explosive growth in biometric personal authentication systems that are closely connected with measurable physical unique characteristics (hand geometry, iris scan, finger prints or DNA) or behavioural features. Human signatures provide secure means for confirmation and authorization in legal documents. So nowadays, automatic signature verification becomes an essential component. In order to convey the state-of-the-art in the field to researchers, in this paper we present a survey of off-line signature verification systems. Copyright © 2011 ACM.
Qiao, Y, Sarma, JMN & Tang, B 2011, 'On Isomorphism Testing of Groups with Normal Hall Subgroups', 28TH INTERNATIONAL SYMPOSIUM ON THEORETICAL ASPECTS OF COMPUTER SCIENCE (STACS 2011), 28th International Symposium on Theoretical Aspects of Computer Science (SATCS), SCHLOSS DAGSTUHL, LEIBNIZ CENTER INFORMATICS, Dortmund, GERMANY, pp. 567-578.
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Reim, KF, Michelberger, P, Lee, KC, Nunn, J, Langford, NK & Walmsley, AI 2011, 'Single-photon-level memory at room temperature', Optics InfoBase Conference Papers.
Reim, KF, Michelberger, P, Lee, KC, Nunn, J, Langford, NK & Walmsley, IA 2011, 'Single-photon-level memory at room temperature', Optics InfoBase Conference Papers.
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We present an efficient broadband optical single-photon-level room-temperature memory, capable of operating with a low unconditional noise floor in the quantum regime, with memory efficiencies exceeding 30% and storage times of up to 4 μs. © 2011 Optical Society of America.
Reim, KF, Michelberger, P, Lee, KC, Nunn, J, Langford, NK & Walmsley, IA 2011, 'Single-photon-level memory at room temperature', 2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference, CLEO EUROPE/EQEC 2011.
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Quantum memories capable of storing single photons are essential building blocks for quantum information processing, enabling the storage and transfer of quantum information over long distances [1]. Devices operating at room temperature can be deployed on a large scale and integrated into existing photonic networks, but so far warm quantum memories have been susceptible to noise at the single photon level [2]. Using a fundamentally different approach to quantum memories, i.e. the recently developed far off-resonant Raman memory scheme [3], we present a highly efficient room-temperature memory that is able to operate with a low unconditional noise floor in the quantum regime, something that no other room-temperature memory has been able to demonstrate before. The quantum memory is operated in warm caesium vapour, and the long-lived, 9.2 GHz hyperfine-split states of the caesium D2 line serve as ground and storage states. The laser fields are 15 GHz detuned from the excited state. © 2011 IEEE.
Reim, KF, Michelberger, P, Lee, KC, Nunn, J, Langford, NK & Walmsley, IA 2011, 'Single-photon-level memory at room temperature', 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
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We present an efficient broadband optical single-photon-level room-temperature memory, capable of operating with a low unconditional noise floor in the quantum regime, with memory efficiencies exceeding 30% and storage times of up to 4 μs. © 2011 OSA.
Son, JB, Lee, JH, Guan, H, Loo, YC & Blumenstein, M 2010, 'ANN-based structural element performance model for reliable bridge asset management', Proceedings of Incorporating Sustainable Practice in Mechanics of Structures and Materials - Proceedings of the 21st Australian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Taylor & Francis, Melbourne, Victoria, pp. 775-780.
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Bridge Management Systems (BMSs) have been developed to assist in the management of a large bridge network. Historical condition ratings obtained from bridge inspections are major resources for predicting future deteriorations via BMSs. Available historical condition ratings in most bridge agencies, however, are very limited, and thus posing a major barrier for predicting reliable future structural performance. To alleviate this problem, A Backward Prediction Model (BPM) technique has been developed to help generate missing historical condition ratings which is crucial for bridge deterioration models to be able to predict more accurate solutions. Nevertheless, there are still considerable limitations in the existing bridge deterioration models. In view of this, feasibility study ofTime Delay Neural Network (TDNN) using BPM-generated historical condition ratings is conducted as an alternative to existing bridge deterioration models. It is anticipated that the TDNN using BPM-generated data can lead to further improvement of the current BMS outcome. © 2011 Taylor & Francis Group, London.
Walmsley, IA, Nunn, J, Langford, N, Datta, A, Zhang, L, Smith, B, Thomas-Peter, N, Spring, J, Metcalf, B, Englland, D, Reim, K, Michelberger, P & Champion, T 2011, 'Building multimode quantum optical networks', Optics InfoBase Conference Papers.
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Light offers a route to the generation of macroscopic quantum states based on both multiple photons (e.g. Schrödinger kittens) and multiple modes (e.g. Dicke-Werner). The combination of these approaches affords new possibilities in both fundamental physics and in technological applications. The routes to building scalabl networks embodying such systems from feasible laboratory resources will be discussed. © 2011 OSA.
Walmsley, IA, Nunn, J, Langford, N, Reim, K, Michelberger, P & Champion, T 2011, 'Photonic quantum memories', Optics InfoBase Conference Papers.
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We survey the state of the art in photonic quantum memories, describing different approaches to the storage and manipulation of quantum light beams and pulses, and expected applications.
Walmsley, IA, Nunn, J, Langford, N, Reim, K, Michelberger, P & Champion, T 2011, 'Photonic quantum memories', 2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference, CLEO EUROPE/EQEC 2011.
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We survey the state of the art in photonic quantum memories, describing different approaches to the storage and manipulation of quantum light beams and pulses, and expected applications. © 2011 IEEE.
Wilde, MM & Hsieh, MH 2011, 'Entanglement boosts quantum turbo codes', IEEE International Symposium on Information Theory - Proceedings, IEEE International Symposium on Information Theory, IEEE, St. Petersburg, Russia, pp. 445-449.
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One of the unexpected breakdowns in the existing theory of quantum serial turbo coding is that a quantum convolutional encoder cannot simultaneously be recursive and non-catastrophic. These properties are essential for a quantum turbo code to have an unbounded minimum distance and for its iterative decoding algorithm to converge, respectively. Here, we show that the entanglement- assisted paradigm gives a theoretical and simulated turbo boost to these codes, in the sense that an entanglement-assisted quantum (EAQ) convolutional encoder can possess both of the aforementioned desirable properties, and simulation results indicate that entanglement-assisted turbo codes can operate reliably in a noise regime 5.5 dB beyond that of standard quantum turbo codes. Entanglement is the resource that enables a convolutional encoder to satisfy both properties because an encoder acting on only information qubits, classical bits, gauge qubits, and ancilla qubits cannot simultaneously satisfy them. Simulation results demonstrate that interleaved serial concatenation of EAQ convolutional encoders leads to a powerful code construction with excellent performance on a memoryless depolarizing channel. © 2011 IEEE.
Zhang, H, Zhang, Y, Ying, M & Zhou, Y 2011, 'Translating first-order theories into logic programs', IJCAI International Joint Conference on Artificial Intelligence, International Joint Conference on Artificial Intelligence, AAAI Press, Barcelona, pp. 1126-1131.
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This paper focuses on computing first-order theories under either stable model semantics or circumscription. A reduction from first-order theories to logic programs under stable model semantics over finite structures is proposed, and an embedding of circumscription into stable model semantics is also given. Having such reduction and embedding, reasoning problems represented by first-order theories under these two semantics can then be handled by using existing answer set solvers. The effectiveness of this approach in computing hard problems beyond NP is demonstrated by some experiments.